Need definitions of: Dark; Warm; and Bright

Critical listening - the practice of evaluating the quality of audio equipment by careful analytical listening - is very different from listening for pleasure. The goal isn't to enjoy the musical experience, but to determine if a system or component sounds good or bad, and which specific characteristics [emphasis in original] of the sound make it good or bad. You want to critically examine what you're hearing so that you can form judgments about the reproduced sound. You can then use this information to evaluate and choose components, and to fine tune a system for greater musical enjoyment.